Fetal rat hypothalami will be transplanted to the anterior chamber of adult rat eyes, and their ultrastructural features examined after a period of maturation. Immunocytochemical localization of gonadotropin releasing hormone will be further documented. Similar evaluations will be made of hypothalami and hemipituitaries after being transplanted together into the anterior chamber of the eye. The transplanted hypothalamus preparation will be used to examine the effects of gonadal steroids and other compounds on the isolated hypothalamus, with special reference to gonadotropin releasing hormone and catecholamine contents. The hypothalamo-pituitary transport preparation will be used to explore hypothalamo-pituitary function in an isolated setting.